This invention relates to the art of image reading and reproducing apparatus, in which an original image is read photoelectrically and subjected to image processing to produce image data, in accordance with which recording light is modulated and used to expose a recording material such as a light-sensitive material, thereby recording an image on it. The invention particularly relates to an image reading and reproducing apparatus which is suitable for use with digital photoprinters which read the image on a film photoelectrically and print it on a light-sensitive material (photographic paper) by exposure through scanning with optical beams modulated in accordance with the digital image data.
The original image is read photoelectrically with a scanner (image reading apparatus) using an image sensor such as a CCD (charge coupled device) sensor to obtain associated image data, which is subjected to image processing in an image processor (image processing apparatus) to produce image data for image recording, which is supplied to a printer (image recording apparatus) to give a reproduced image. This type of image reading and reproducing apparatus is used in various kinds of printers, photographic printing apparatus, printing platemaking apparatus, etc.
Conventionally, the image recorded on a photographic film such as a negative or a reversal film (these films are hereinafter referred to simply as "a film" or "films" depending on the case) is printed on a light-sensitive material such as a photographic paper mostly by a technique called "direct exposure", in which the light-sensitive material is subjected to areal exposure by means of projected light carrying the information of the image on the film.
In recent years, digital photoprinters, or printing apparatus which utilize a digital image recording system, have been commercialized. In digital photoprinters, the projected light from the original film is read with a scanner to provide digital data representing the image recorded on the film; the digital image data is then sent to the image processor, where it is subjected to various image processing steps such as color/density correction, edge enhancement and tone correction, thereby producing recording image data (exposure conditions), which are sent to a printing unit, where the light-sensitive material is exposed by scanning with optical beams modulated in accordance with the image so as to record an image (latent image) and the exposed light-sensitive material is developed to produce a finished print having a visual image.
In the digital photoprinters, the image recorded on the original film is successively read frame by frame with the scanner and sent sequentially to the image processor, where it is subjected to image processing, with the resulting image data being transferred sequentially to the printing unit.
The printer has a memory for storing several frames of the image and the image data sent from the image processor is stored in the memory before it is retrieved on a FIFO basis to perform the desired image recording.
Therefore, in apparatus such as digital photoprinters which perform continuous image reading and reproducing operations, it is preferred for the purpose of accomplishing efficient and high-speed image recording, namely, for outputting the finished prints efficiently, that the retrieved image data are successively subjected to image processing to perform successive recording. Referring to the scanner, it is preferred that as soon as the reading operation ends, it reads the next frame of an image.
In other words, it is preferred that there is no possibility for the continuous reading and image processing operations to be suspended on account of the image recording with the printer or that the printer will not be forced into a state where it waits for the next image data to be transferred from the image processor; alternatively, each part of the apparatus should be in operation at all times to enable the outputting of finished prints.
Speaking of the scanner, image processor and printer as individual functional parts, they are each preferred to be capable of high throughputs per unit time. On the other hand, the reading and recording times will vary with several factors such as the size of the original, the magnification of the output image and the size of the finished print.
Therefore, with an image reading and reproducing apparatus, particularly one of a type that performs continuous image reading and recording operations, it is required that the individual functional parts such as the scanner, image processor and printer exhibit their performance to the fullest extent thereby achieving high efficiency in image recording, or the outputting of finished prints.